The Specific Aims of the Inhalation Core are to provide housing of mice prior to inhalation experiments in a pathogen-free environment and controlled exposures to asbestos and ovalbumin (OVA). The objective of the Transgenic Mouse Core is to provide transgenic mice to the members of the Program Project. The generation, maintenance and screening of new and previously generated conventional transgenic mice will be centralized in this Core. In addition, this Core aims to develop a new experimental approach that involves stable integration of bacterial artificial chromosomes (BACs) in the mouse genome. The Specific Aims of this Core are: i. To provide a Core service for the generation of new transgenic mice (F2 C3H x C57Bl/6) expressing specific transgenes in pulmonary epithelial cells. The new transgenic mice that are proposed in this Program Project will be generated in the University of Vermont Transgenic Mouse Core, directed by Dr. Rincon. ii. To centralize the backcross process required to obtain each of the new and previously generated transgenic mice in two specific strain backgrounds. The new F2 C3H x C57Bl/6 transgenic mice will be backcrossed for seven generations with wild type inbred mice (C57Bl/6 and Balb/c) to obtain homogeneous genetic background. iii. To screen transgenic mice by molecular analyses of genomic DNA (PCR, slot blot) and provide the necessary number of mice to the investigators of the Program. The screening process will also be centralized to prevent variability and increase efficiency and reproducibility of the results from different projects. iv. To develop new applications involving the use of transgenic mice to study lung fibrosis. An alternative approach to complement the classical transgenic mouse models will be developed during the Program funding period: the generation of transgenic mice by BACs.